This invention relates to the use of reductants in the ozone in the treatment of dental caries.
The great destructive disease of teeth is dental caries which may be defined as the acid dissolution of enamel, dentine or cementum as a consequence of the metabolism of micro-organisms living within deposits on the teeth known a plaque. Dental caries is believed to be associated with specific micro-organisms, the principal ones being Streptococcus Mutans, Lactobacilli, Actinomyces Visosus Serovar 2, Actinomyces Naeslundii and xe2x80x9cIntermediatexe2x80x9d Actinomyces, other Streptococci and yeasts. These are acid producing micro-organisms which produce acids such as acetic and lactic acids from the dietary carbohydrates. The micro-organisms associated with dental caries are unique and are ecologically very different from those associated with, for example, infected root canals.
Dental caries is currently managed by one or more of the following:
(i) preventive treatment by, for example, dietary and oral hygiene measures and may include the topical application of chemotherapeutic agents;
(ii) the removal of dentine exhibiting the signs of active caries;
(iii) the protection of any newly exposed non-carious dentine with restorative material.
Measures aimed at the prevention or the arrest of dental caries are mainly based on the elimination of dental plaque from the surfaces of roots and the institution of dietary controls to reduce the frequency and quantity of readily fermentable carbohydrate ingestion. The mechanical removal of plaque has been a major platform for the prevention of dental caries for some time. However, this poses special problems in the case of primary root caries due to access problems. Because dentine has a Knoop hardness of 68 in contrast to enamel at 11, the mechanical removal of plaque from its surface inevitably results in some loss of tissue also. Toothbrush abrasion is now a very common phenomenon and invariably leads to the loss of root dentine from the facial aspects of teeth. Consequently, the traditional methods of plaque control in the prevention of dental caries create further problems even when access permits it to be used effectively.
Conventional caries removal and cavity preparation entail the use of high and low speed handpieces. However, disadvantages of this system include the perception that drilling is unpleasant for patients and local anesthetic is frequently required. Furthermore, handpieces are expensive to purchase and maintain and their use may lead to the removal of softened but uninfected dentine resulting in the excessive loss of tooth tissue.
Where restoration is required, all materials used to restore carious lesions have their limitations. For example, gold and ceramic are expensive and present a technical challenge for the practitioner. While amalgam is durable, predictable material, it has poor aesthetic qualities, is potentially toxic and may cause allergic reactions in some people.
It is an object of the invention to alleviate the disadvantages of the prior art.
It has now unexpectedly been found that ozone can penetrate carious tissue and can therefore be used in the treatment of dental caries.
According to the present invention there is provided the use of ozone in the preparation of a therapeutic system for the treatment of dental caries.
As used herein, the term xe2x80x9cozonexe2x80x9d is intended to embrace pure ozone, oxonised air and ozonized aqueous media, such as water optionally containing a reductant, such as thiocyanate or peppermint.
The ozone is delivered at a pressure sufficient to penetrate the carious tissue and at a concentration and for a period of time sufficient to kill substantially all of the micro-organisms within the carious lesion.
Preferably, a needle-sized jet of pure ozone or ozonized air in a shroud of micro-organism-free aqueous medium, e.g. water optionally containing a reductant, is injected at the desired location.
If desired, a sealant of the type known in the art may be applied to a carious lesion following ozone treatment.
The advantages using ozone in the treatment of dental caries include the following:
1. It eliminates drilling and its attendant problems;
2. It is rapid and painless;
3. It does not require sophisticated methods of isolating the tooth;
4. No local anesthetic is required.
The invention is illustrated in the following Examples. Unless otherwise stated, the ozone delivered in the following Examples is present in air at a concentration of 5.2%,
Many studies concerning the clinical evaluation of ozone have been based on assessments of its harmful effects rather than demonstrating any therapeutic benefits it may offer. Ozone is one of nature""s most powerful oxidants which accounts for its ability to kill bacteria, spores and viruses. Uniquely, ozone decomposes to a harmless, non-toxic and environmentally safe material (oxygen). In this investigation, a multicomponent evaluation of the oxidative consumption of salivary biomolecules by ozone (O3) has been performed using high resolution proton (1H) nuclear magnetic resonance (NMR) spectroscopy. The ozone-generating equipment employed in this study was designed by Purezone Ltd. (Ipswich, U.K.). Unstimulated human saliva samples were collected from 8 patients and each of them was divided into two equivalent portions (0.60 ml). The first of these was treated with O3 generated from the above device for a period of 30 seconds; the second group of portions served as controls. Samples were subjected to 1H NMR analysis at an operating frequency of 600 MHz. Results acquired revealed that O3 treatment gave rise to (1) the oxidative decarboxylation of the salivary electron-donor pyruvate (generating acetate and CO2, as products), (2) oxidation of the volatile sulphur compound precursor methionine to its corresponding sulphoxide and (3) the oxidative consumption of salivary polyunsaturated fatty acids. Moreover, evidence for the O3-mediated oxidation of salivary 3-D-hydroxybutyrate was also obtained. High field 1H NMR spectroscopy provides much useful analytical data regarding the fate of O3 in human saliva, information which is of much relevance to its potential therapeutic actions in vivo.
Primary root carious lesions (PRCL) are a major clinical problem. The aim of this study was to establish if ozone could achieve effective microbial killing in PRCL. An ozone producing generator (Purezone Ltd., Ipswich, U.K.) was used in this ex-vivo study assessing the use of ozone on PRCL. In this study, soft PRCL requiring restoration were used as these are the most severe type of lesion found in humans. 20 freshly extracted teeth with PRCL requiring restoration were used. After plaque removal using a hand held standard fine nylon fiber sterile toothbrush with sterile water as a lubricant to cleanse the surface, each tooth was then isolated using sterile cotton wool rolls and dried using a dry sterile cotton wool roll. A sample of PRCL was taken using a sterile excavator from half of the most active part of the lesion. Subsequently, 10 seconds of the ozonized water was applied to the lesion and another sample was taken from the other half of the most active part of the lesion. Each sample was weighed and immediately placed in 1 ml of Fastidious Anaerobe Broth (FAB). To each 1 ml of FAB containing a biopsy o carious or ozone treated carious dentine, sterile glass beads were added. They were vortexed for 30 seconds to facilitate the extraction of any micro-organisms from the carious dentine and disperse any aggregates. After decimal dilution with FAB, 100 ml aliquots of these was spread on Fastidious Anaerobe Agar (LabM, Bury, Lancs., U.K.) supplemented with 5% (V/V) horse blood in an anaerobic chamber at 37xc2x0 C. for four days. The meanxc2x1SE number of each colony type was counted and calculated.
Using the paired Student t-test a significant difference (p less than 0.001) was observed between the two groups. Clearly, the percentage of micro-organisms killed associated with the use of ozone was more than 99%.
The procedure of Example 2 was repeated except that ozonized water was applied to the lesion for 20 seconds. Using the paired student t-test, a significant difference was observed in the ozonized water group (log10 3.77xc2x10.42, meanxc2x1SE) compared with the control group (log10 6.18xc2x10.21) (p less than 0.001).
The results of these tests show that the use of ozone can provide an effective, rapid and simple means for killing micro-organisms in carious lesions.
These has been little research on the interaction between primary root carious lesions (PRCL) and adhesive materials. The aim of this study was to examine the shear bond strength of four adhesive systems to PRCL with sound dentine acting as a control. The adhesive systems used were:
1. OptiBond FL Prime1/OptiBond FL Adhesive1/OptiGuard1 
1Kerr, Romulus, Mich., U.S.A.; 
2. OptiBond FL Prime/OptiGuard
3. OptiGuard and
4. ChemFil II2 
2Dentsply, Konstanz, Germany. 
The materials were applied to sound radicular dentine and PRCL in vitro in freshly extracted teeth. The bonding site was macroscopically intact, was flat and had at least a 3.5 mm diameter. 37% phosphoric acid was used for 15 seconds in samples in groups 1- greater than 3 whilst 25% polyacrylic acid was used in group 4. After bonding the samples were stored for seven days in a moist atmosphere at 37xc2x0 C. A shearing force was applied at 1 mm/minute. There were at least 10 samples in each group. The mean (s.e.) shear bond strengths were (MPa);
While statistical testing showed that the shear bond strength of the OptiBond FL Prime/OptiBond FL Adhesive/OptiGuard was significantly the highest, (p less than 0.001), the caries status of the root surface had no significant influence on the bond strength. OptiGuard in combination with OptiBond FL Prime and OptiBond Adhesive had the highest bond strength and this was not influenced by the caries status of the surface.
The aims of these studies were to evaluate the efficiency of ozone on primary root caries and associated micro-organisms (Streptococcus sobrinus; TH 21 Streptococcus mutans; NCTC 10449). In study 1, 40 soft primary root carious lesions (PRCLs) from freshly extracted teeth were used and randomly divided into two groups to test the exposure to ozone for either 10 or 20 seconds. There was a significant (p less than 0.001) difference (Meanxc2x1SE) between the control samples for either 10 seconds (log10 5.91xc2x10.15) or 20 seconds (log10 6.18xc2x10.21) and ozone treated samples for either 10 seconds (log10 3.57xc2x10.37) or 20 seconds (log10 3.77xc2x10.42). In study 2, 40 sterile saliva coated glass beads were put into bijoux bottles with 3 mls of Todd Hewitt broth for control and test groups. S. sobrinus and S. mutans were inoculated and incubated anaerobically overnight. Each glass bead was washed with 2 mls of PBS. Immediately, 10 seconds of ozone was applied to the glass beads in the test groups. Subsequently, each glass bead in the test and control groups was placed in 3 mls of Todd Hewitt broth with six more sterile glass beads and were vortexed for 30 seconds. After decimal dilutions, 100 ml aliquots were spread on blood agar plates supplemented with 5% (V/V) horse blood and placed in an anaerobic chamber at 37xc2x0 C. for two days. The number of each colony type was counted and calculated. Using the paired student t-test, there was a significant reduction (p less than 0.0001) (Meanxc2x1SE) between the control samples for S. sobrinus (log10 4.61xc2x10.13) and S. mutans (log10 3.93xc2x10.07) and ozone treated samples for S. sobrinus (log10 1.09xc2x10.36). This treatment regime is therefore an effective, quick, conservative and simple method to kill micro-organisms in primary root carious lesions.
The present invention further relates to apparatus and formulations for the treatment of dental caries utilizing an oxidizing gas.
The role of specific micro-organism such as, for example, streptococcus mutants in dental caries is well documented. Enzymes produced by such micro-organisms synthesize dextran from the sucrose passing through the month with food or drink resulting in the formation of dental plaque and dental caries.
Dental caries is the decay of teeth caused by demineralization of the enamel surface with organic acids produced by bacteria which adhere to teeth surfaces.
Heretofore, dental caries have been removed through the use of conventional grinding handpieces, lasers and air-blasting apparatus. However high-speed turbine drills or low-speed drills unfortunately will grind both caries and sound dentine. Accordingly, a practitioner must select and grind only caries and consequently, this method depends upon this skill of the practitioner. Lasers have been utilized to remove caries, however, not much success has been achieved for varies reasons. For example, blackened charred tissue blocks the laser radiation which, in turn, prevents the laser from reaching caries therebelow. In addition, heating also interrupts the ablation process.
With regard to air-blasting treatment of caries sound, dentine may also be easily removed, and accordingly, the skill of the practitioner is of outmost importance.
The present invention provides for the treatment of caries without the disadvantages of the prior art hereinabove noted.
Apparatus for the treatment of dental caries in accordance with the present invention generally includes a source of oxidizing gas and a handpiece for delivering the gas to a tooth. A cup attached to the handpiece, is provided for receiving the gas and exposing a selected area of the tooth to the gas.
The cup may include a resilient edge for sealably engaging the tooth around the selected area to prevent escape of the gas therepast. Alternatively, a suitable sealant may be utilized for providing the sealed engagement between the cup and the tooth. This enables a totally closed system for the application of the gas to the tooth.
A source of oxidizing gas may include an ozone generator and an ozone pump. An aspiration pump may be provided, along with an aspiration line connected to the handpiece, for enabling circulation of the gas into and out of a cup chamber subtending the cup edge. In that regard a controller may be provided for regulating the ozone and aspiration pumps in order to circulate the gas into an out of the cup chamber at a pressure insufficient to escape past the sealed engagement between and the tooth.
The apparatus may further include a source of reductant, in fluid communication with the cup chamber and a reductant pump may be provided for circulating the reductant through the cup chamber in order to flush the oxidizing gas from the cup chamber and into the aspiration line.
A waste accumulator may be provided and connected to the aspiration line for receiving the reductant. In addition, a filter may be provided for removal of any residual oxidizing gas from the aspiration line.
In one embodiment of the present invention the cup edge includes a relatively uniform perimeter for sealably engaging a tooth between a cusp and a gingiva. In another embodiment of the present invention, a cup edge may include a contour enabling a sealably engagement with adjacent teeth. More specifically, the cupped edge may have a perimeter contoured for sealably engaging cusps of adjacent teeth.